These types of housings are typically manufactured from aluminum for aluminum electrolyte capacitors, for example. Such capacitors are attached to mounting plates individually or also in banks. Since the aluminum housing of the capacitor typically has the potential of the anode or the cathode applied to it, the housing must be electrically insulated to the outside. In particular, cup-like housings whose cup floors are attached flat on a mounting plate must be electrically insulated in relation to this plate.
When aluminum electrolyte capacitors are loaded with high currents, heat is generated which must be dissipated outward. The mounting plates for the capacitors are generally made of metal and are then used as heat sinks for dissipating the waste heat. The maximum current carrying capacity of the capacitor improves with improved heat dissipation from the capacitor. Then, for example, the number of capacitors may be reduced with the same current carrying capacity in capacitor banks.
The housing of the capacitors must therefore be electrically insulated in relation to the mounting plates made of metal, but good heat conduction between the capacitor housing and the mounting plates must also be possible. For this reason, air gaps between the floor of the housing and the mounting plate are to be avoided, since they are only very poor heat conductors.
Housings for electrolyte capacitors are frequently electrically insulated in that the wall of the housing is covered with an electrically insulating covering, for example, a heat-shrinkable sleeve made of plastic. A plastic cap is positioned on the floor of the housing, which is shrunk into the heat-shrinkable sleeve. When such a housing is mounted on a mounting plate, a planar air gap results at the floor of the cup, so that the heat dissipation from the housing via the plate is impaired.
A housing for electrochemical capacitors in which the floor of the housing and adjoining regions of the wall of the housing are enclosed by a plastic cup which is covered by a heat-shrinkable sleeve is known from the patent specification DE 198 11 862 C1. This housing has the disadvantage that the wall thicknesses of the plastic cup are relatively thick for reasons of injection molding technology, so that only poor heat conduction may be ensured between the mounting plate and the housing through the plastic cup. Furthermore, the mounting of this housing is relatively complicated, since, among other things, the heat-shrinkable sleeve must be pulled over the plastic cup, which is connected with difficulties due to the wall thicknesses of the plastic cup. In addition, the plastic cup must be tailored to the shape of each individual construction of each capacitor, which makes the production of different capacitor types having this housing construction more difficult. Because of the separate shaping for the plastic cup and the housing, very narrow manufacturing tolerances are also to be maintained in order to ensure a tight fit of the plastic cup on the housing without air gaps.